Light-Emitting Device, Electronic Device, Lighting Device, and Method for Manufacturing the Light-Emitting Device

ABSTRACT

A light-emitting device in which deterioration of an organic EL element due to impurities such as moisture or oxygen is suppressed is provided. The light-emitting device includes a first substrate and a second substrate facing each other, a light-emitting element provided over the first substrate, a first sealant provided so as to surround the light-emitting element, and a second sealant provided so as to surround the first sealant. One of the first sealant and the second sealant is a glass layer and the other is a resin layer. A dry agent is provided in a first space surrounded by the first sealant, the second sealant, the first substrate, and the second substrate, or in the resin layer. The light-emitting element is included in a second space surrounded by the first sealant, the first substrate, and the second substrate.

This application is a divisional of copending U.S. application Ser. No.13/591,445, filed on Aug. 22, 2012 which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a light-emitting device, an electronicdevice, and a lighting device each using organic electroluminescence(EL). The present invention also relates to a method for manufacturingthe light-emitting device.

BACKGROUND ART

A light-emitting element (also referred to as an organic EL element)using organic EL has been actively researched and developed. In thefundamental structure of an organic EL element, a layer containing alight-emitting organic compound is provided between a pair ofelectrodes. By voltage application to this element, light emission fromthe light-emitting organic compound can be obtained.

An organic EL element, which has characteristics such as feasibility ofbeing thinner and lighter, high speed response to input signals, andcapability of direct current low voltage driving, has been expected tobe applied to next-generation flat panel displays or lighting devices.In particular, a display device in which organic EL elements arearranged in matrix is considered to have advantages of a wide viewingangle and excellent visibility over a conventional liquid crystaldisplay device.

However, an organic EL element has a problem in that entry of impuritiessuch as moisture or oxygen from the outside erodes the reliability.

When impurities such as moisture or oxygen enter an organic compound ora metal material contained in an organic EL element from the outside ofthe organic EL element, the lifetime of the organic EL element issignificantly shortened in some cases. This is because an organiccompound or a metal material contained in the organic EL element reactswith the impurities such as moisture or oxygen and thus deteriorates.

Thus, a technique to seal an organic EL element for preventing entry ofimpurities has been researched and developed.

An organic EL element can be sealed with a thin film, glass using glassfrit or the like, or a resin, for example. The technique to seal anorganic EL element with a thin film has problems such as high cost andlow productivity. The sealing property of a resin is lower than that ofglass and it is difficult to completely block impurities such asmoisture or oxygen. In contrast, it is considered that a technique toseal an organic EL element with a pair of substrates and glass usingglass frit or the like is a preferable sealing method because of its lowcost and high productivity.

For example, a glass package sealed by attaching a first glass plate toa second glass plate with frit, which can be applied to seal an organicEL element, is disclosed in Patent Document 1.

REFERENCE [Patent Document 1] United States Published Patent ApplicationNo. 2004/0207314 DISCLOSURE OF INVENTION

However, in a light-emitting device whose organic EL element is sealedwith a pair of glass substrates and glass frit, a sufficient effect ofsealing cannot be obtained in some cases because the strength of a glasslayer formed with the glass frit is not sufficient or the adhesionstrength of the glass frit to a material in contact with the glass fritis not sufficient.

For example, glass frit is generally irradiated with a laser and melted,so that the glass frit is adhered to a substrate. By heat generated atthis time, a residual strain is generated in a glass layer formed withthe glass frit. In the manufacturing process of the light-emittingdevice, part of the glass layer might be separated from the substrate orbreaking or cracking (hereinafter, collectively referred to as a crack)might be generated in the glass layer by stress in the glass layercaused by the residual strain. In some cases, the stress is concentratedin a surface of the glass substrate to cause a crack in the glasssubstrate.

When part of the glass layer is separated from the substrate or a crackis generated in the glass layer or the glass substrate in themanufacturing process, the effect of sealing is reduced. Thus, anorganic compound or a metal material contained in the organic EL elementreacts with impurities such as moisture or oxygen which enter from theoutside of the light-emitting device and thus deteriorates.

Accordingly, one object of one embodiment of the present invention is toprovide a light-emitting device which is capable of suppressingdeterioration of an organic EL element due to impurities such asmoisture or oxygen.

One object of one embodiment of the present invention is to provide ahighly reliable electronic device or a highly reliable lighting device,including the light-emitting device.

One object of one embodiment of the present invention is to provide amethod for manufacturing a light-emitting device which is capable ofsuppressing entry of impurities such as moisture or oxygen.

A light-emitting device of one embodiment of the present invention hasthe following structure: glass having excellent productivity and anexcellent sealing property, and a resin having excellent impactresistance and excellent heat resistance, which is not easily broken bydeformation due to external force or the like, are used to seal anorganic EL element with a pair of substrates. Further, a dry agent isprovided in a space surrounded by the pair of substrates, the glass, andthe resin or contained in the resin.

Specifically, one embodiment of the present invention is alight-emitting device including a first substrate and a second substratewhich face each other, a light-emitting element provided over the firstsubstrate, a first sealant provided so as to surround the light-emittingelement, and a second sealant provided so as to surround the firstsealant. The light-emitting element includes a layer containing alight-emitting organic compound between a pair of electrodes. One of thefirst sealant and the second sealant is a glass layer and the other ofthe first sealant and the second sealant is a resin layer. A dry agentis provided in a first space surrounded by the first sealant, the secondsealant, the first substrate, and the second substrate. Thelight-emitting element is provided in a second space surrounded by thefirst sealant, the first substrate, and the second substrate.

One embodiment of the present invention is a light-emitting deviceincluding a first substrate and a second substrate which face eachother, a light-emitting element provided over the first substrate, afirst sealant provided so as to surround the light-emitting element, anda second sealant provided so as to surround the first sealant. Thelight-emitting element includes a layer containing a light-emittingorganic compound between a pair of electrodes. One of the first sealantand the second sealant is a glass layer and the other of the firstsealant and the second sealant is a resin layer. A dry agent is includedin the resin layer and the light-emitting element is provided in a spacesurrounded by the first sealant, the first substrate, and the secondsubstrate.

Note that in this specification, the first sealant and the secondsealant are not necessarily in contact with the first substrate and thesecond substrate. The first sealant may be in contact with a first filmformed over the first substrate or a second film formed over the secondsubstrate, for example.

In the above light-emitting device of one embodiment of the presentinvention, one of the first sealant and the second sealant is the glasslayer and the other is the resin layer. In addition, the dry agent isprovided in the space (hereinafter, referred to as the first space)surrounded by the first sealant, the second sealant, the firstsubstrate, and the second substrate, or contained in the resin layer.

In one embodiment of the present invention, the glass layer, which has ahigh effect of sealing, is used as the sealant. In addition, the resinlayer, which has better impact resistance and heat resistance than theglass layer and is not easily broken by deformation due to externalforce or the like, is used as the other sealant, in one embodiment ofthe present invention.

Owing to the resin layer, which has excellent impact resistance andexcellent heat resistance and is not easily broken by deformation due toexternal force or the like and is used as the other sealant, deformationof the light-emitting device due to external force or the like can besuppressed. Accordingly, generation of a crack in the glass layer usedas the sealant or the substrate can be suppressed.

Further, the resin layer is less likely to be separated from thesubstrate or a crack is less likely to be generated in the resin layerin the manufacturing process or in use of the light-emitting device, sothat the effect of sealing the organic EL element with the resin layeris less likely to be reduced. Thus, even when part of the glass layer isseparated from the substrate or a crack is generated in the glass layerin the manufacturing process or in use of the light-emitting device andthe effect of sealing the organic EL element with the glass layer is notsufficiently obtained, the effect of sealing the organic EL element withthe resin layer is maintained in the light-emitting device of oneembodiment of the present invention.

Furthermore, since the dry agent is provided in the first space or inthe resin layer, entry of impurities such as moisture or oxygen into thespace (hereinafter also referred to as the second space) surrounded bythe pair of substrates and the first sealant can be suppressed.

When impurities such as moisture or oxygen enter the second space, themoisture or oxygen enters the organic EL element. Even when a dry agentis provided in the second space, moisture or oxygen is adsorbed by thedry agent and at the same time (concurrently), moisture or oxygen entersthe organic EL element.

However, in one embodiment of the present invention, the dry agent isprovided in the first space or in the resin layer. In the case where thedry agent is provided in the first space, impurities such as moisture oroxygen are adsorbed by the dry agent provided in the first space evenwhen the sealing property of the second sealant is insufficient and thusthe impurities enter the first space. As a result, entry of theimpurities into the second space can be suppressed. In the case wherethe dry agent is contained in the resin layer, the sealing property ofthe resin layer can be improved and thus, entry of impurities such asmoisture or oxygen into the second space (and the first space in thecase where the resin layer containing the dry agent is the secondsealant) can be suppressed. As a result, an organic compound or a metalmaterial contained in the organic EL element can be prevented fromreacting with impurities such as moisture or oxygen which enter theorganic EL element and deteriorating.

When the light-emitting device has the structure in which the dry agentis contained in the resin layer, the size of the light-emitting deviceand the area other than the light-emitting region (i.e., the area of theframe) can be further reduced compared to the structure in which the dryagent is provided in the first space. In addition, for example, a stepof providing a depressed portion for providing a dry agent over thesubstrate is not necessary, so that cost reduction and simplification ofthe manufacturing process can be achieved.

The light-emitting device preferably has a structure in which the firstsealant is the glass layer and the second sealant is the resin layer.

In the light-emitting device, distortion due to external force or thelike increases toward the peripheral portion. Thus, in the first sealantand the second sealant provided so as to surround the first sealant, theglass layer can be used as the first sealant, where distortion due toexternal force or the like is relatively small, so that the sealingproperty of the glass layer can be prevented from being insufficient. Inaddition, the second sealant can be the resin layer, which has excellentimpact resistance and excellent heat resistance and is not easily brokenby deformation due to external force or the like; thus, entry ofmoisture or oxygen into the first space can be suppressed by the sealingproperty of the resin and by the dry agent included in the first spaceor contained in the resin layer. Accordingly, even when the sealingproperty of the glass layer is insufficient, entry of moisture or oxygeninto the second space (or the organic EL element) can be suppressed.

In the light-emitting device, a resin contained in the resin layer ispreferably a photocurable resin. A photocurable resin, which is cured bylight irradiation, is preferably used because change in film quality anddeterioration of an organic EL material itself caused when the organicEL element is heated can be suppressed.

One embodiment of the present invention is an electronic deviceincluding the light-emitting device. One embodiment of the presentinvention is a lighting device including the light-emitting device. Inthe light-emitting device, deterioration of the organic EL element dueto impurities such as moisture or oxygen can be suppressed. Thus, ahighly reliable electronic device or a highly reliable lighting devicecan be provided.

One embodiment of the present invention is a method for manufacturing alight-emitting device, including a first step, a second step, a thirdstep, a fourth step, and a fifth step in that order. In the first step,a first electrode, a layer containing a light-emitting organic compound,and a second electrode are provided in that order over a first substrateto form a light-emitting element, whereby a light-emitting portion isformed. In the second step, a frit paste is applied over a secondsubstrate and then is heated to form a glass layer. In the third step, aphotocurable resin containing a dry agent is applied over the secondsubstrate in an inert atmosphere to form a resin layer. In the fourthstep, the first substrate and the second substrate are provided so as toface each other and the resin layer is irradiated with light underreduced pressure, so that a closed space surrounded by the resin layer,the first substrate, and the second substrate is formed. In the fifthstep, the glass layer is irradiated with laser light in the air, so thata closed space surrounded by the glass layer, the first substrate, andthe second substrate is formed. The glass layer is provided so as tosurround the light-emitting portion and the resin layer is provided soas to surround the glass layer.

In the method for manufacturing a light-emitting device, the fifth stepis performed in the air. It is preferable in that a laser irradiationapparatus does not necessarily has a complicated structure (a laserirradiation apparatus with a simple structure can be used).

In general, the sealing property of a glass layer is insufficient beforethe glass layer is irradiated with laser light. Thus, deterioration ofan organic EL element due to impurities occurs when a light-emittingdevice is exposed to the air. In contrast, the fourth step is performedin one embodiment of the present invention, so that the organic ELelement is sufficiently sealed with the photocurable resin containingthe dry agent and the pair of substrates. Accordingly, entry ofimpurities such as moisture or oxygen into the light-emitting element todeteriorate the light-emitting element can be suppressed even when thefifth step is performed in the air.

Further, in the method for manufacturing a light-emitting device, thefourth step is performed under reduced pressure. With the fourth stepperformed under reduced pressure, the space where the organic EL elementis sealed with the photocurable resin containing the dry agent and thepair of substrates keeps its reduced pressure. Thus, the state wherepressure is applied to the pair of substrates by atmospheric pressure ismaintained in the fifth step performed in the air, so that laser lightirradiation can be performed without providing any other pressureapplication.

As a result, in the above-described light-emitting device of oneembodiment of the present invention, the second space (space surroundedby the first sealant, the first substrate, and the second substrate) ispreferably under reduced pressure.

In one embodiment of the present invention, a light-emitting devicewhich is capable of suppressing deterioration of an organic EL elementdue to impurities such as moisture or oxygen can be provided.

In one embodiment of the present invention, a highly reliable electronicdevice or a highly reliable lighting device, including thelight-emitting device can be provided.

In one embodiment of the present invention, a method for manufacturing alight-emitting device which is capable of suppressing entry ofimpurities such as moisture or oxygen can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B illustrate light-emitting devices of one embodiment ofthe present invention.

FIGS. 2A and 2B illustrate light-emitting devices of one embodiment ofthe present invention.

FIGS. 3A to 3C illustrate a method for manufacturing a light-emittingdevice, according to one embodiment of the present invention.

FIGS. 4A to 4C illustrate a method for manufacturing a light-emittingdevice, according to one embodiment of the present invention.

FIGS. 5A and 5B illustrate a light-emitting device of one embodiment ofthe present invention.

FIGS. 6A to 6C illustrate EL layers of one embodiment of the presentinvention.

FIGS. 7A to 7E illustrate electronic devices of one embodiment of thepresent invention.

FIG. 8 illustrates lighting devices of one embodiment of the presentinvention.

FIGS. 9A to 9C illustrate an electronic device of one embodiment of thepresent invention.

FIGS. 10A1, 10A2, 10B1, 10B2, 10C1, and 10C2 illustrate light-emittingdevices of one embodiment of the present invention.

FIGS. 11A to 11D illustrate a light-emitting device in Example.

FIGS. 12A to 12C illustrate light-emitting devices in Example.

FIGS. 13A1, 13A2, 13B1, 13B2, 13C1, 13C2, 13D1, and 13D2 show results inExample.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments and an example will be described in detail with reference tothe drawings. Note that the present invention is not limited to thefollowing description. It will be readily appreciated by those skilledin the art that modes and details of the present invention can bemodified in various ways without departing from the spirit and scope ofthe present invention. The present invention therefore should not beconstrued as being limited to the following description of theembodiments and the example. Note that in structures of the presentinvention described below, the same portions or portions having similarfunctions are denoted by the same reference numerals in differentdrawings, and a description thereof is not repeated.

Embodiment 1

In this embodiment, light-emitting devices of one embodiment of thepresent invention will be described with reference to FIGS. 1A and 1Band FIGS. 2A and 2B.

The light-emitting device of one embodiment of the present inventionincludes one or more light-emitting elements between a first substrateand a second substrate which face each other. The light-emitting elementincludes a layer containing a light-emitting organic compound(hereinafter referred to as an EL layer) between a pair of electrodes.The light-emitting element is sealed with a first sealant which isprovided along the peripheries of the first substrate and the secondsubstrate to surround the light-emitting element. Further, thelight-emitting element is sealed with a second sealant which is providedalong the peripheries of the first substrate and the second substrate tosurround the first sealant. One of the first sealant and the secondsealant is a glass layer and the other is a resin layer. In addition, adry agent is provided in a space (hereinafter referred to as a firstspace) surrounded by the first sealant, the second sealant, the firstsubstrate, and the second substrate or contained in the resin layer.

In one embodiment of the present invention, the glass layer, which has ahigh effect of sealing, and the resin layer, which has better impactresistance and heat resistance than the glass layer and is not easilybroken by deformation due to external force or the like, are used as thesealants.

Owing to the resin layer, which has excellent impact resistance andexcellent heat resistance and is not easily broken by deformation due toexternal force or the like and is used as one of the sealants,deformation of the light-emitting device due to external force or thelike can be suppressed. Accordingly, generation of a crack in the glasslayer used as the other of the sealants or the substrate can besuppressed.

Further, the resin layer is less likely to be separated from thesubstrate or a crack is less likely to be generated in the resin layerin the manufacturing process or in use of the light-emitting device, sothat the effect of sealing the organic EL element with the resin layeris less likely to be reduced. Thus, even when part of the glass layer isseparated from the substrate or a crack is generated in the glass layeror the substrate in the manufacturing process or in use of thelight-emitting device and the effect of sealing the organic EL elementwith the glass layer is not sufficiently obtained, the effect of sealingthe organic EL element with the resin layer is maintained in thelight-emitting device of one embodiment of the present invention.

Furthermore, since the dry agent is provided in the first space or inthe resin layer, entry of impurities such as moisture or oxygen into aspace (hereinafter referred to as a second space) surrounded by the pairof substrates and the first sealant can be suppressed.

Here, the case where a dry agent is neither provided in the first spacenor in the resin layer but provided in the second space is described.The sealing property of the glass layer, which is the first sealant orthe second sealant, might be insufficient because a crack is generatedin the manufacturing process of the light-emitting device, for example.Although the resin layer which is the first sealant or the secondsealant (the sealant which is not the glass layer) and does not containa dry agent has a sealing property, the sealing property is lower thanthat of the glass layer. Since a dry agent is not provided in the firstspace, more than a little moisture or oxygen probably enters the secondspace. In the second space at this time, moisture or oxygen is adsorbedby the dry agent and at the same time (concurrently), moisture or oxygenenters the organic EL element.

However, in the light-emitting device of one embodiment of the presentinvention, the dry agent is provided in the first space or in the resinlayer. In the case where the dry agent is provided in the first space,impurities such as moisture or oxygen are adsorbed by the dry agentprovided in the first space even when the sealing property of the secondsealant is insufficient and thus the impurities enter the first space.As a result, entry of the impurities into the second space can besuppressed. In the case where the dry agent is contained in the resinlayer, the sealing property of the resin layer can be improved and thus,entry of impurities such as moisture or oxygen into the second space(and the first space in the case where the resin layer containing thedry agent is the second sealant) can be suppressed. As a result, anorganic compound or a metal material contained in the organic EL elementcan be prevented from reacting with impurities such as moisture oroxygen which enter the organic EL element and deteriorating.

<Structural Example of Light-Emitting Device of the Present Invention>Structural Example 1

FIG. 1A illustrates a plan view of a light-emitting device of oneembodiment of the present invention. FIG. 1A also illustrates across-sectional view taken along dashed-dotted line A-B in the planview.

The light-emitting device illustrated in FIG. 1A includes alight-emitting portion 802 including a light-emitting element over afirst substrate 801. In the light-emitting device, a first sealant 805 ais provided so as to surround the light-emitting portion 802 and asecond sealant 805 b is provided so as to surround the first sealant 805a.

The light-emitting portion 802 is sealed with the first substrate 801, asecond substrate 806, and the first sealant 805 a, and with the firstsubstrate 801, the second substrate 806, and the second sealant 805 b.

Note that in this specification, as described above, the first sealantand the second sealant are not necessarily in contact with the firstsubstrate and the second substrate. The first sealant 805 a may be incontact with an insulating film or a conductive film formed over thefirst substrate 801, for example.

In the light-emitting device illustrated in FIG. 1A, the first sealant805 a is a resin layer containing a dry agent and the second sealant 805b is a glass layer. Since the dry agent is contained in the resin layer,the sealing property of the first sealant 805 a is sufficiently high.

With the resin layer, generation of a crack in the glass layer can besuppressed. As described above, in the case where a sufficient effect ofsealing the light-emitting element with the glass layer, which is thesecond sealant 805 b, cannot be obtained, entry of impurities such asmoisture or oxygen into a second space 811 can be suppressed owing to ahigh sealing property of the first sealant 805 a even when impuritiessuch as moisture or oxygen enter a first space 813. As a result, anorganic compound or a metal material contained in the organic EL elementcan be prevented from reacting with impurities such as moisture oroxygen which enter the organic EL element and deteriorating.

Further, since the first sealant 805 a is provided, even when degassingfrom the glass layer, which is the second sealant 805 b, occurs, entryof the gas into the second space 811 (or the organic EL element) can besuppressed.

Structural Example 2

FIG. 1B illustrates a plan view of a light-emitting device of oneembodiment of the present invention. FIG. 1B also illustrates across-sectional view taken along dashed-dotted line A-B in the planview.

The light-emitting device illustrated in FIG. 1B is similar to thelight-emitting device in Structural Example 1, except that the firstsealant 805 a is the glass layer and the second sealant 805 b is theresin layer containing the dry agent.

The light-emitting device illustrated in FIG. 1B includes the dry agentin the resin layer; thus, the sealing property of the second sealant 805b is sufficiently high. Accordingly, entry of impurities such asmoisture or oxygen into the first space 813 and the second space 811 canbe suppressed. As a result, an organic compound or a metal materialcontained in the organic EL element can be prevented from reacting withimpurities such as moisture or oxygen which enter the organic EL elementand deteriorating.

In the light-emitting device, distortion due to external force or thelike increases toward the peripheral portion. Thus, in the first sealant805 a and the second sealant 805 b provided so as to surround the firstsealant 805 a, the glass layer can be used as the first sealant 805 a,where distortion due to external force or the like is relatively small,so that the sealing property of the glass layer can be prevented frombeing insufficient. In addition, the second sealant 805 b can containthe dry agent and the resin, which has excellent impact resistance andexcellent heat resistance and is not easily broken by deformation due toexternal force or the like; thus, entry of moisture or oxygen into thefirst space 813 can be suppressed. Accordingly, even when the sealingproperty of the glass layer is insufficient, entry of moisture or oxygeninto the second space 811 (or the light-emitting portion 802 or thelight-emitting element) can be suppressed.

Although the dry agent is contained in the resin layer which is used asthe sealant in Structural Example 1 and Structural Example 2, thepresent invention is not limited thereto. A dry agent may be provided inthe first space as in Structural Example 3 and Structural Example 4described later.

Since the dry agent is contained in the resin layer in StructuralExample 1 and Structural Example 2, the size of the light-emittingdevice and the area other than the light-emitting region (i.e., the areaof the frame) can be further reduced compared to Structural Example 3and Structural Example 4 described later. In addition, a depressedportion or the like for providing a dry agent in the first space 813 isnot necessarily formed, so that cost reduction and simplification of themanufacturing process can be achieved.

Structural Example 3

FIG. 2A is a cross-sectional view of a light-emitting device of oneembodiment of the present invention.

The light-emitting device illustrated in FIG. 2A is similar to thelight-emitting device in Structural Example 1, except that a firstsealant 805 c is a resin layer which does not contain a dry agent andthe first space 813 includes a dry agent 815.

The light-emitting portion 802 is sealed with the first substrate 801,the second substrate 806, and the first sealant 805 c, and with thefirst substrate 801, the second substrate 806, and the second sealant805 b.

When a sufficient effect of sealing the light-emitting element with theglass layer, which is the second sealant 805 b, cannot be obtained andimpurities such as moisture or oxygen enter the first space 813, theimpurities such as moisture or oxygen are adsorbed by the dry agent 815included in the first space 813. Thus, entry of the impurities into thesecond space 811 through the first sealant 805 c can be suppressed. As aresult, an organic compound or a metal material contained in the organicEL element can be prevented from reacting with impurities such asmoisture or oxygen which enter the organic EL element and deteriorating.

Further, since the dry agent 815 is included in the first space 813,even when degassing from the glass layer, which is the second sealant805 b, occurs, entry of the gas into the second space 811 (or theorganic EL element) can be suppressed.

Structural Example 4

FIG. 2B is a cross-sectional view of a light-emitting device of oneembodiment of the present invention.

The light-emitting device illustrated in FIG. 2B is similar to thelight-emitting device in Structural Example 2, except that a secondsealant 805 d is a resin layer which does not contain a dry agent andthe first space 813 includes the dry agent 815.

The light-emitting portion 802 is sealed with the first substrate 801,the second substrate 806, and the first sealant 805 a, and with thefirst substrate 801, the second substrate 806, and the second sealant805 d.

As described above, in the light-emitting device, distortion due toexternal force or the like increases toward the peripheral portion.Thus, in the first sealant 805 a and the second sealant 805 d providedso as to surround the first sealant 805 a, the glass layer can be usedas the first sealant 805 a, where distortion due to external force orthe like is relatively small, so that the sealing property of the glasslayer can be prevented from being insufficient. In addition, the resinlayer, which has excellent impact resistance and excellent heatresistance and is not easily broken by deformation due to external forceor the like, can be used as the second sealant 805 d; thus, the sealingproperty of the second sealant 805 d can be maintained.

Even when impurities such as moisture or oxygen enter the first space813 through the second sealant 805 d, the impurities are adsorbed by thedry agent 815 included in the first space 813. As a result, fewerimpurities are contained in the first space 813, and thus even when thesealing property of the glass layer is insufficient, entry of theimpurities into the second space 811 (or the light-emitting portion 802or the light-emitting element) can be suppressed.

In Structural Example 3 and Structural Example 4, the dry agent isprovided separately from the sealant, and thus a material for the resinthat can be used for the sealant and a material for the dry agent can beselected from a wider range than Structural Example 1 and StructuralExample 2.

Note that the structure of a light-emitting device of one embodiment ofthe present invention is not limited to Structural Examples 1 to 4. Forexample, a light-emitting device of one embodiment of the presentinvention may have a structure in which one of the first sealant and thesecond sealant is the glass layer and the other is the resin layercontaining the dry agent, and a dry agent is further provided in thefirst space.

<Materials That Can Be Used for Light-Emitting Device of One Embodimentof the Present Invention>

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention will be described below.

[Substrate]

For each of the first substrate 801 and the second substrate 806, amaterial such as glass, quartz, or an organic resin can be used. Thesubstrate on the side from which light from the light-emitting elementis extracted is formed using a material which transmits the light.

In the case where an organic resin is used for the substrate, any of thefollowing can be used as the organic resin, for example: polyesterresins such as polyethylene terephthalate (PET) and polyethylenenaphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, apolymethylmethacrylate resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polyamide resin, a cycloolefin resin, apolystyrene resin, a polyamide imide resin, a polyvinylchloride resin,and the like. Further, a substrate in which a glass fiber is impregnatedwith an organic resin or a substrate in which an inorganic filler ismixed with an organic resin can also be used.

Note that an insulating layer is preferably provided on a surface of thesubstrate to prevent impurities contained in the substrate fromdiffusing into elements provided over the substrate.

[Light-Emitting Portion 802]

The light-emitting portion 802 includes an organic EL element as thelight-emitting element. The organic EL element includes a layercontaining a light-emitting organic compound between a pair ofelectrodes (an anode and a cathode). A method for driving the organic ELelement is not limited, and may be either an active matrix method or apassive matrix method. Further, any of a top emission structure, abottom emission structure, and a dual emission structure can be used.Specific structure and material of the organic EL element will bedescribed later.

Note that any of a color filter method, a separate coloring method, anda color conversion method may be used for the light-emitting device ofone embodiment of the present invention.

[Sealant]

The glass layer used as the sealant can be formed with glass fit, forexample. A glass ribbon can also be used. The glass fit or the glassribbon contains at least a glass material.

The glass frit contains a glass material as a frit material, forexample, magnesium oxide, calcium oxide, strontium oxide, barium oxide,cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadiumoxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide,lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide,iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobiumoxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide,lithium oxide, antimony oxide, lead borate glass, tin phosphate glass,vanadate glass, or borosilicate glass. The glass frit preferablycontains at least one or more kinds of transition metals to absorbinfrared light.

In order to form the glass layer with the glass frit, a frit paste isapplied over the substrate, for example. The frit paste contains thefrit material and a resin (also referred to as a binder) diluted by anorganic solvent. The fit paste can be formed using a known material andcan have a known structure. For example, terpineol, n-butyl carbitolacetate, or the like can be used as the organic solvent andethylcellulose or the like can be used as the resin.

An absorber which absorbs light having a wavelength of laser light maybe added to the frit material.

Thermal expansion coefficients of the substrate and the glass layer arepreferably close to each other. As the thermal expansion coefficientsare closer to each other, generation of a crack in the glass layer orthe substrate due to thermal stress can be further suppressed.

The resin layer used as the sealant can be formed using a known materialincluding a photocurable resin such as an ultraviolet curable resin, athermosetting resin, or the like. In particular, a material that is notpermeable to moisture or oxygen is preferably used.

In particular, a photocurable resin is preferably used. The organic ELelement contains a material with low heat resistance in some cases. Aphotocurable resin, which is cured by light irradiation, is preferablyused because change in film quality and deterioration of the organic ELmaterial itself caused when the organic EL element is heated can besuppressed.

[Dry Agent]

For the dry agent provided in the resin layer or in the first space, aknown material can be used. For the dry agent, a substance which adsorbsmoisture and the like by chemical adsorption or a substance whichadsorbs moisture and the like by physical adsorption can be used. Anoxide of an alkali metal, an oxide of an alkaline earth metal (e.g.,calcium oxide or barium oxide), sulfate, a metal halide, perchlorate,zeolite, and silica gel can be given as examples thereof.

A method for providing the dry agent in the space is not particularlylimited and for example, the dry agent can be provided in the space inthe following manner: the space is filled with a filler containing thedry agent, or a drying means including the dry agent is provided (forexample, an organic material containing the dry agent is applied, a dishincluding the dry agent is attached, or powder of the dry agent isapplied) over the first substrate or the second substrate.

[Space]

The first space 813 and the second space 811 are, for example, filledwith an inert gas such as a rare gas or a nitrogen gas, or an organicresin. Further, the space is in an atmospheric pressure state or areduced pressure state.

As described above, in the light-emitting device of one embodiment ofthe present invention, one of the first sealant and the second sealantis the glass layer having excellent productivity and an excellentsealing property, and the other is the resin layer having excellentimpact resistance and excellent heat resistance, which is not easilybroken by deformation due to external force or the like. In addition,the dry agent is provided in the first space or in the resin layer inthe light-emitting device of one embodiment of the present invention.Accordingly, entry of impurities such as moisture or oxygen into thesecond space can be suppressed.

Thus, in accordance with one embodiment of the present invention, alight-emitting device in which deterioration of an organic EL elementdue to impurities such as moisture or oxygen is suppressed can beprovided.

This embodiment can be combined with any of the other embodiments asappropriate.

Embodiment 2

In this embodiment, a method for manufacturing a light-emitting device,according to one embodiment of the present invention will be describedwith reference to FIGS. 3A to 3C and FIGS. 4A to 4C. In particular,Structural Example 2 (see FIG. 1B) described in Embodiment 1 will bedescribed as an example.

{First Step: Formation of Light-Emitting Portion}

The light-emitting portion 802 is formed over the first substrate 801(FIG. 3A). Specifically, the organic EL element, a transistor forcontrolling light emission of the organic EL element, and the likeincluded in the light-emitting portion 802 are formed. In the case of anactive matrix light-emitting device, a driver circuit portion or thelike may be provided in addition to the light-emitting portion 802. Astructural example of the active matrix light-emitting device will bedescribed in detail in Embodiment 3.

{Second Step: Formation of Sealant 1—Glass Layer—}

In this embodiment, the glass layer is formed with glass frit. First, afrit paste is formed over the second substrate 806 (FIG. 3B). The fritpaste is formed by a printing method such as a screen printing method,or a dispensing method or the like.

Then, the frit paste is heated (pre-baked) to form the first sealant 805a, which is the glass layer. At this time, the heating temperature ispreferably close to the glass transition point of a frit material thatis used. For example, the heating temperature can be approximately 300°C. to 400° C.

The top surface of the glass layer is preferably flat to increase theadhesion to the first substrate 801. Thus, planarization treatment suchas application of pressure may be performed. The planarization treatmentcan be performed before or after the pre-baking.

The first sealant 805 a is provided so as to surround the light-emittingportion 802 when the second substrate 806 is provided to face the firstsubstrate 801.

Note that the glass layer is subjected to laser irradiation (mainbaking) in a later step (fifth step). A structure in which thelight-emitting portion 802 and the first sealant 805 a are not incontact with each other after the light-emitting portion 802 is sealedwith the first substrate 801, the second substrate 806, and the firstsealant 805 a in a fourth step is preferable because thermal damage tothe light-emitting portion 802 due to the laser irradiation can besuppressed (deterioration of an organic compound or the like containedin the light-emitting portion 802 can be suppressed).

{Third Step: Formation of Sealant 2—Resin Layer—}

The second sealant 805 b is formed over the second substrate 806 so asto surround the first sealant 805 a (FIG. 3C). The second sealant 805 bis the resin layer containing the dry agent in Structural Example 2.

The second sealant 805 b is preferably formed in an inert atmosphere(e.g., a rare gas atmosphere or a nitrogen atmosphere) or under reducedpressure. In the case where the second sealant 805 b is formed in anenvironment where a large amount of impurities such as moisture arecontained, e.g., in the air, heat treatment as dehydration treatment ispreferably performed after the formation of the second sealant 805 b.

In this embodiment, the second sealant 805 b is formed using aphotocurable resin containing a dry agent in an inert atmosphere.

Note that the glass layer is subjected to laser irradiation in a laterstep (fifth step). The first sealant 805 a and the second sealant 805 bare preferably not in contact with each other because thermal damage tothe second sealant 805 b due to the laser irradiation can be suppressed(deterioration of a resin or the like contained in the second sealant805 b can be suppressed).

In general, heat resistance of an organic compound included in anorganic EL element is not high; thus, the glass layer is preferablyprovided over the second substrate 806 (substrate over which the organicEL element is not formed). In contrast, the photocurable resin may beprovided either over the first substrate 801 or over the secondsubstrate 806.

In the case where Structural Example 1 (FIG. 1A) is manufactured, theresin layer containing the dry agent is provided in the third step so asto surround the light-emitting portion 802 and so as to be surrounded bythe glass layer (the second sealant 805 b).

Further, in the case where Structural Example 3 or 4 (FIG. 2A or 2B) ismanufactured, the dry agent is provided in the first space 813 beforethe fourth step. For example, the dry agent can be provided in a spacesurrounded by the first sealant 805 a and the second sealant 805 b afterthe first sealant 805 a and the second sealant 805 b are formed over thesecond substrate 806. Furthermore, in the case where the second space811 is filled with a filler, the filling is performed before the fourthstep.

{Fourth Step: Sealing with Resin Layer}

The first substrate 801 and the second substrate 806 are bonded to eachother (FIG. 4A). The first substrate 801 and the second substrate 806are bonded to each other so that the resin layer (the second sealant 805b) is closely in contact with the substrates.

Then, the photocurable resin is irradiated with light so as to be cured,whereby the first space 813, which is a closed space surrounded by theresin layer, the first substrate, and the second substrate, is formed(FIG. 4B).

The light irradiation may be performed from the first substrate 801 sideor the second substrate 806 side. Further, a shielding plate ispreferably used so that the light-emitting portion 802 and the like areprevented from being irradiated with ultraviolet light.

The above bonding step is performed in an inert atmosphere (e.g., a raregas atmosphere or a nitrogen atmosphere) or under reduced pressure.Accordingly, impurities such as moisture or oxygen are less likely to becontained in the first space 813 and the second space 811. The bondingstep is preferably performed while the external pressure is applied.

In this embodiment, the bonding step is performed under reducedpressure.

{Fifth Step: Sealing with Glass Layer}

The glass layer is irradiated with laser light, whereby the second space811, which is a closed space surrounded by the glass layer, the firstsubstrate, and the second substrate, is formed (FIG. 4C). The glasslayer is melted by the laser light and is bonded to the first substrate801 and the second substrate 806 at their respective connectionportions. After that, the glass layer is solidified.

The laser light irradiation is preferably performed while the externalpressure is applied so that the adhesion between the glass layer (thefirst sealant 805 a) and the first substrate 801, and the adhesionbetween the glass layer and the second substrate 806 can be improved (abubble generation from the glass layer can be suppressed). In thisembodiment, the laser light irradiation is performed under atmosphericpressure. Since the fourth step (the step of bonding the first substrate801 and the second substrate 806 to each other) is performed underreduced pressure, the first space 813 and the second space 811 keeptheir reduced pressure. Thus, the state where pressure is applied to thefirst substrate 801 and the second substrate 806 by atmospheric pressureis maintained under atmospheric pressure, so that the laser lightirradiation can be performed without providing any other pressureapplication.

The laser light irradiation is preferably performed in the air. When thelaser light irradiation is performed in the air, a laser irradiationapparatus is not necessarily provided in a nitrogen atmosphere, a vacuumatmosphere, or the like, whereby a laser irradiation apparatus having asimple structure can be used. At the time when the fourth step isfinished, the light-emitting device is sealed with the second sealant,which is the resin layer containing the dry agent, and the pair ofsubstrates. Accordingly, even when the light-emitting device is exposedto the air, entry of impurities such as moisture or oxygen in the airinto the light-emitting device can be suppressed.

In general, the sealing property of a glass layer is insufficient beforethe glass layer is irradiated with laser light. Thus, impurities enterand an organic EL element deteriorates when a light-emitting device isexposed to the air. In contrast, the fourth step is performed in oneembodiment of the present invention, so that the organic EL element issealed with the resin layer containing the dry agent and the pair ofsubstrates. Accordingly, entry of impurities such as moisture or oxygeninto the light-emitting element to deteriorate the light-emittingelement can be suppressed even when the fifth step is performed in theair.

In this embodiment, the laser light irradiation is performed from thesecond substrate 806 side. Thus, the second substrate 806 is formedusing a material which transmits the laser light. The laser lightirradiation can be performed from the first substrate 801 side. However,in the case where a wiring or the like is formed between the firstsubstrate 801 and the glass layer, the glass layer might not besufficiently irradiated with the laser light. Accordingly, the laserlight irradiation is preferably performed from the second substrate 806side.

As the laser light, laser light having a wavelength which allows thelaser light to transmit a substrate on the side irradiated with thelaser light and energy which is large enough to heat the glass layer isused. As the laser light, an Nd:YAG laser, a semiconductor laser, or thelike is preferably used.

As described above, in accordance with one embodiment of the presentinvention, a method for manufacturing a light-emitting device in whichentry of impurities such as moisture or oxygen is suppressed can beprovided.

Modification Examples

Although an example where one light-emitting portion 802 is formed overone first substrate 801 is described in this embodiment, one embodimentof the present invention is not limited thereto. A plurality of thelight-emitting portions 802 are formed over the first substrate 801 inthe first step, the second to fifth steps are performed, and then thefirst substrate 801 is divided, so that a plurality of light-emittingdevices can be obtained from one first substrate 801.

In the case where the plurality of the light-emitting portions 802 areformed over one first substrate 801 as illustrated in FIGS. 10A1, 10B1,and 10C1, the first sealants 805 a (glass layer in FIGS. 10A1, 10A2,10B1, 10B2, 10C1, and 10C2) are provided so as to surround therespective light-emitting portions 802.

The second sealant 805 b (resin layer containing the dry agent in FIGS.10A1, 10A2, 10B1, 10B2, and 10C1) can be provided so as to surround eachof the first sealants 805 a as illustrated in FIG. 10A1. Alternatively,adjacent second sealants 805 b each surrounding the first sealant 805 amay be connected to each other as illustrated in FIG. 10B1.

One embodiment of the present invention is not limited to a structure inwhich the second sealants 805 b surround the respective first sealants805 a. For example, a structure illustrated in FIG. 10C1 can beemployed. In FIG. 10C1, the second sealant 805 b is provided along thefour sides of the first substrate 801 so as to surround all the firstsealants 805 a.

Each of the modification examples illustrated in FIGS. 10A1, 10B1, and10C1 can be divided into four light-emitting devices each of which isprovided with the light-emitting portion 802. Specifically, each of thefour light-emitting devices obtained by dividing the structure in FIG.10A1 is a light-emitting device illustrated in FIG. 10A2, each of thefour light-emitting devices obtained by dividing the structure in FIG.10B1 is a light-emitting device illustrated in FIG. 10B2, and each ofthe four light-emitting devices obtained by dividing the structure inFIG. 10C1 is a light-emitting device illustrated in FIG. 10C2.

The structure in FIG. 10A1 is preferable because the division can beeasily performed in a region where neither the second substrate 806 northe second sealant 805 b is formed. The structure in FIG. 10B1 ispreferable because a wide light-emitting region (area occupied by thelight-emitting portion 802 in the substrate) can be obtained compared tothe structure in FIG. 10A1.

In the light-emitting device illustrated in FIG. 10C2, which is obtainedby dividing the structure in FIG. 10C1 into four light-emitting devices,the light-emitting portion 802 is sealed with the pair of substrates andthe first sealant 805 a, but not with the second sealant 805 b.

However, the light-emitting portion 802 is sealed with the pair ofsubstrates and the first sealant 805 a, and with the pair of substratesand the second sealant 805 b until the structure in FIG. 10C1 isdivided. For example, even in the case where the fourth step isperformed under reduced pressure and the fifth step is performed in theair as described above, entry of impurities into the organic EL elementis suppressed. As described above, entry of impurities such as moistureor oxygen into the organic EL element in the manufacturing process ofthe light-emitting device can be suppressed. Thus, it can be said thatthe light-emitting device illustrated in FIG. 10C2 is an example of alight-emitting device manufactured using the method for manufacturing alight-emitting device, according to one embodiment of the presentinvention.

The light-emitting device illustrated in FIG. 10C2, in which thelight-emitting portion 802 is sealed with the pair of substrates and thefirst sealant 805 a and the second sealant 805 b is not included, ispreferable because entry of impurities such as moisture or oxygen intothe organic EL element in the manufacturing process can be suppressedand the area of the frame can be reduced.

This embodiment can be combined with any of the other embodiments asappropriate.

Embodiment 3

In this embodiment, a light-emitting device of one embodiment of thepresent invention will be described with reference to FIGS. 5A and 5B.FIG. 5A is a plan view of the light-emitting device of one embodiment ofthe present invention and FIG. 5B is a cross-sectional view taken alongdashed-dotted line E-F in FIG. 5A.

An active matrix light-emitting device according to this embodimentincludes, over the first substrate 801, the light-emitting portion 802,a driver circuit portion 803 (gate side driver circuit portion), and adriver circuit portion 804 (source side drive circuit portion). Thefirst sealant 805 a is provided so as to surround the light-emittingportion 802, the driver circuit portion 803, and the driver circuitportion 804, and the second sealant 805 b is provided so as to surroundthe first sealant 805 a. Thus, the light-emitting portion 802 and thedriver circuit portions 803 and 804 are sealed in the second space 811surrounded by the first substrate 801, the second substrate 806, and thefirst sealant 805 a. Further, the light-emitting portion 802 and thedriver circuit portions 803 and 804 are sealed in the first space 813surrounded by the first substrate 801, the second substrate 806, and thesecond sealant 805 b.

In this embodiment, the first sealant 805 a is the glass layer and thesecond sealant 805 b is the resin layer containing the dry agent.

In the light-emitting device of this embodiment, the resin layer is lesslikely to be separated from the substrate or a crack is less likely tobe generated in the resin layer in the manufacturing process or in useof the light-emitting device because the resin layer has excellentimpact resistance and excellent heat resistance and is not easily brokenby deformation due to external force or the like, so that the effect ofsealing the organic EL element with the resin layer is less likely to bereduced.

Thus, even when part of the glass layer is separated from the substrateor a crack is generated in the glass layer or the substrate in themanufacturing process or in use of the light-emitting device and aneffect of sealing the light-emitting element with the glass layer is notsufficiently obtained, the effect of sealing the light-emitting elementwith the resin layer is maintained in the light-emitting device of oneembodiment of the present invention.

Further, since the dry agent is contained in the resin layer, entry ofimpurities such as moisture or oxygen into the second space 811surrounded by the pair of substrates and the first sealant can besuppressed. As a result, an organic compound or a metal materialcontained in the organic EL element can be prevented from reacting withimpurities such as moisture or oxygen which enter the organic EL elementand deteriorating.

Over the first substrate 801, a lead wiring for connecting an externalinput terminal through which a signal (e.g., a video signal, a clocksignal, a start signal, or a reset signal) or a potential from theoutside is transmitted to the driver circuit portions 803 and 804 isprovided. Here, an example is described in which a flexible printedcircuit (FPC) 808 is provided as the external input terminal. Note thata printed wiring board (PWB) may be attached to the FPC 808. In thisspecification, the light-emitting device includes in its category thelight-emitting device itself and the light-emitting device on which theFPC or the PWB is mounted.

The driver circuit portions 803 and 804 include a plurality oftransistors. FIGS. 5A and 5B each illustrate an example in which thedriver circuit portion 803 includes a CMOS circuit which is acombination of an n-channel transistor 152 and a p-channel transistor153. A circuit included in the driver circuit portion can be formedusing a variety of types of circuits such as a CMOS circuit, a PMOScircuit, or an NMOS circuit. In this embodiment, a driver-integratedtype in which a driver circuit and the light-emitting portion are formedover the same substrate is described; however, the present invention isnot limited to this structure, and a driver circuit can be formed over asubstrate that is different from the substrate over which alight-emitting portion is formed.

The light-emitting portion 802 includes a plurality of light-emittingunits each including a switching transistor 140 a, a current controltransistor 140 b, and the first electrode 118 electrically connected toa wiring (a source electrode or a drain electrode) of the currentcontrol transistor 140 b. Further, an insulating layer 124 is formed soas to cover an end portion of the first electrode 118.

A light-emitting element 130 includes the first electrode 118, a layercontaining a light-emitting organic compound (EL layer) 120, and asecond electrode 122.

<Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention>

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention will be described below. Notethat the materials described as examples in Embodiment 1 can be used forthe substrate, the sealant, and the dry agent.

[Transistor]

There is no particular limitation on the structure of the transistor(e.g., the transistor 140 a, 140 b, 152, or 153) used in thelight-emitting device of one embodiment of the present invention. Atop-gate transistor or a bottom-gate transistor such as invertedstaggered transistor may be used. In addition, there is no particularlimitation on a material used for the transistor.

A gate electrode can be formed to have a single layer structure or astacked-layer structure using any of metal materials such as molybdenum,titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, andscandium, and an alloy material which contains any of these elements,for example.

A gate insulating layer can be formed to have a single layer structureor a stacked-layer structure using any of silicon oxide, siliconnitride, silicon oxynitride, silicon nitride oxide, and aluminum oxideby a plasma CVD method, a sputtering method, or the like, for example.

A semiconductor layer can be formed using a silicon semiconductor or anoxide semiconductor. As the silicon semiconductor, a single crystalsilicon semiconductor, a polycrystalline silicon semiconductor, or thelike can be used as appropriate. As the oxide semiconductor,In—Ga—Zn—O-based metal oxide or the like can be used as appropriate.Note that the semiconductor layer is preferably formed using an oxidesemiconductor which is In—Ga—Zn—O-based metal oxide so as to have lowoff-state current, in which case an off-state leakage current of thelight-emitting element 130 to be formed later can be reduced.

A source electrode layer and a drain electrode layer can be formed usinga metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo,and W, a metal nitride film containing any of these elements (e.g., atitanium nitride film, a molybdenum nitride film, or a tungsten nitridefilm), or the like. Alternatively, a film of a high-melting-point metalsuch as Ti, Mo, or W or a metal nitride film thereof (e.g., a titaniumnitride film, a molybdenum nitride film, or a tungsten nitride film) maybe formed over or/and below a metal film such as an Al film or a Cufilm. Further alternatively, the source electrode layer and the drainelectrode layer may be formed using a conductive metal oxide. As theconductive metal oxide, indium oxide (In₂O₃ or the like), tin oxide(SnO₂ or the like), zinc oxide (ZnO), indium tin oxide (ITO), indiumoxide-zinc oxide (In₂O₃—ZnO or the like), or any of these metal oxidematerials in which silicon oxide is contained can be used.

A first insulating layer 114 has an effect of preventing diffusion ofimpurities into a semiconductor included in the transistor. As the firstinsulating layer 114, an inorganic insulating film such as a siliconoxide film, a silicon oxynitride film, or an aluminum oxide film can beused.

As a second insulating layer 116, an insulating film with aplanarization function is preferably selected to reduce surfaceunevenness due to the transistor. For example, an organic material suchas polyimide, acrylic, or benzocyclobutene can be used. Other than suchorganic materials, it is also possible to use a low-dielectric constantmaterial (low-k material) or the like. Note that the second insulatinglayer 116 may be formed by stacking a plurality of insulating filmsformed using any of these materials.

[Insulating Layer 124]

The insulating layer 124 is formed so as to cover an end portion of thefirst electrode 118. The insulating layer 124 preferably has a curvedsurface with curvature at an upper end portion or a lower end portionthereof to obtain favorable coverage by the second electrode 122 whichis to be formed over the insulating layer 124. For example, it ispreferable that the upper end portion or the lower end portion of theinsulating layer 124 have a curved surface with a radius of curvature(0.2 μm to 3 μm). The insulating layer 124 can be formed using anorganic compound such as a negative photosensitive resin or a positivephotosensitive resin, or an inorganic compound such as silicon oxide orsilicon oxynitride.

[Light-Emitting Element]

The first electrode 118 is provided on the side opposite to a side wherelight is extracted and is formed using a reflective material. As thereflective material, a metal material such as aluminum, gold, platinum,silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium can be used. The metal material or an alloy containing themetal material may contain lanthanum, neodymium, or germanium. Besides,an alloy containing aluminum (an aluminum alloy) such as an alloy ofaluminum and titanium, an alloy of aluminum and nickel, or an alloy ofaluminum and neodymium, or an alloy containing silver such as an alloyof silver and copper can be used. An alloy of silver and copper ispreferable because of its high heat resistance.

The EL layer 120 includes at least a layer (light-emitting layer)containing a light-emitting substance. In addition, the EL layer 120 canhave a stacked-layer structure in which a layer containing a substancehaving a high electron-transport property, a layer containing asubstance having a high hole-transport property, a layer containing asubstance having a high electron-injection property, a layer containinga substance having a high hole-injection property, a layer containing abipolar substance (substance having a high electron-transport propertyand a high hole-transport property), and the like are combined asappropriate. Structural examples of the EL layer will be described indetail in Embodiment 4.

As a light-transmitting material for the second electrode 122, indiumoxide, ITO, indium oxide-zinc oxide, zinc oxide, zinc oxide to whichgallium is added, or the like can be used.

For the second electrode 122, a metal material such as gold, platinum,nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium,or titanium can also be used. A nitride of the metal material (e.g.,titanium nitride) or the like may also be used. Graphene or the like mayalso be used. In the case of using the metal material (or the nitridethereof), the second electrode 122 may be thinned so as to be able totransmit light.

[Color Filter and Black Matrix]

On the second substrate 806, a color filter 166 is provided so as tooverlap with the light-emitting element 130. The color filter 166 isprovided to control the color of light emitted from the light-emittingelement 130. For example, in a full-color display device using whitelight-emitting elements, a plurality of light-emitting units providedwith color filters of different colors are used. In that case, threecolors, red (R), green (G), and blue (B), may be used, or four colors,red (R), green (G), blue (B), and yellow (Y), may be used.

A black matrix 164 is provided between the adjacent color filters 166.The black matrix 164 shields a light-emitting unit from light emittedfrom the light-emitting elements 130 in adjacent light-emitting unitsand prevents color mixture between the adjacent light-emitting units.Here, the color filter 166 is provided so that its end portion overlapswith the black matrix 164, whereby light leakage can be reduced. Theblack matrix 164 can be formed using a material that shields lightemitted from the light-emitting element 130, for example, a metal or anorganic resin. Note that the black matrix 164 may be provided in aregion other than the light-emitting portion 802, for example, in thedriver circuit portion 803.

An overcoat 168 is formed to cover the color filter 166 and the blackmatrix 164. The overcoat 168 is formed using a material that transmitslight emitted from the light-emitting element 130, and can be aninorganic insulating film or an organic insulating film, for exampleNote that the overcoat 168 is not necessarily provided unless needed.

This embodiment can be combined with any of the other embodiments asappropriate.

Embodiment 4

In this embodiment, structural examples of an EL layer which can be usedfor a light-emitting device of one embodiment of the present inventionwill be described with reference to FIGS. 6A to 6C.

A known substance can be used for the EL layer, and either a lowmolecular compound or a high molecular compound can be used. Note thatthe substance for forming the EL layer includes not only an organiccompound but also an inorganic compound in part thereof.

In FIG. 6A, the EL layer 120 is provided between the first electrode 118and the second electrode 122. In the EL layer 120 in FIG. 6A, ahole-injection layer 701, a hole-transport layer 702, a light-emittinglayer 703, an electron-transport layer 704, and an electron-injectionlayer 705 are stacked in that order from the first electrode 118 side.

A plurality of EL layers may be stacked between the first electrode 118and the second electrode 122 as illustrated in FIG. 6B. In that case, acharge generation layer 709 is preferably provided between a first ELlayer 120 a and a second EL layer 120 b which are stacked. Alight-emitting element having such a structure is unlikely to suffer theproblem of energy transfer, quenching, or the like and gives widerchoice of materials, thereby easily having both high light emissionefficiency and a long lifetime. Moreover, it is easy to obtainphosphorescence from one EL layer and fluorescence from the other ELlayer. This structure can be combined with the above-mentioned structureof the EL layer.

By making the EL layers emit light of different colors from each other,the light-emitting element can provide light emission of a desired coloras a whole. For example, by forming a light-emitting element having twoEL layers such that the emission color of the first EL layer and theemission color of the second EL layer are complementary colors, thelight-emitting element can provide white light emission as a whole. Notethat the word “complementary” means color relationship in which anachromatic color is obtained when colors are mixed. In other words, whenlights obtained from substances which emit light of complementary colorsare mixed, white emission can be obtained. This can be applied to alight-emitting element including three or more EL layers.

As illustrated in FIG. 6C, the EL layer 120 may include thehole-injection layer 701, the hole-transport layer 702, thelight-emitting layer 703, the electron-transport layer 704, anelectron-injection buffer layer 706, an electron-relay layer 707, and acomposite material layer 708 which is in contact with the secondelectrode 122, between the first electrode 118 and the second electrode122.

It is preferable to provide the composite material layer 708 which is incontact with the second electrode 122 because damage caused to the ELlayer 120 particularly when the second electrode 122 is formed by asputtering method can be reduced.

By providing the electron-injection buffer layer 706, an injectionbarrier between the composite material layer 708 and theelectron-transport layer 704 can be reduced; thus, electrons generatedin the composite material layer 708 can be easily injected to theelectron-transport layer 704.

The electron-relay layer 707 is preferably formed between theelectron-injection buffer layer 706 and the composite material layer708. The electron-relay layer 707 is not necessarily provided; however,by providing the electron-relay layer 707 having a highelectron-transport property, electrons can be rapidly transported to theelectron-injection buffer layer 706.

In the structure in which the electron-relay layer 707 is providedbetween the composite material layer 708 and the electron-injectionbuffer layer 706, the acceptor substance contained in the compositematerial layer 708 and the donor substance contained in theelectron-injection buffer layer 706 are less likely to interact witheach other, and thus their functions hardly interfere with each other.Accordingly, an increase in driving voltage can be suppressed.

Examples of materials which can be used for each layer will be describedbelow. Note that each layer is not limited to a single layer, and may bea stack of two or more layers.

The hole-injection layer 701 is a layer containing a substance having ahigh hole-injection property. As the substance having a highhole-injection property, for example, a metal oxide such as molybdenumoxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide,chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silveroxide, tungsten oxide, or manganese oxide; or a phthalocyanine-basedcompound such as copper(II) phthalocyanine (abbreviation: CuPc) can beused.

Any of the following aromatic amine compounds which are low molecularorganic compounds can also be used:4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB),4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B),3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2), and3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1).

A high molecular compound can also be used. Examples of the highmolecular compound include poly(N-vinylcarbazole) (abbreviation: PVK),poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), andpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD). A high molecular compound to which acid is added, such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS)or polyaniline/poly(styrenesulfonic acid) (PAni/PSS), can also be used.

In particular, for the hole-injection layer 701, a composite material inwhich an acceptor substance is mixed with an organic compound having ahigh hole-transport property is preferably used. With the use of thecomposite material in which an acceptor substance is mixed with asubstance having a high hole-transport property, excellenthole-injection from the first electrode 118 can be obtained, whichresults in a reduction in driving voltage of the light-emitting element.Such a composite material can be formed by co-evaporation of a substancehaving a high hole-transport property and an acceptor substance. Whenthe hole-injection layer 701 is formed using the composite material,holes are easily injected from the first electrode 118 into the EL layer120.

The organic compound for the composite material is preferably asubstance having a hole mobility of 10⁻⁶ cm²/V·s or higher. Note thatother than the above substances, any substance that has a property oftransporting more holes than electrons may be used. The organiccompounds which can be used for the composite material will bespecifically shown below.

Examples of the organic compound that can be used for the compositematerial are aromatic amine compounds, such as TDATA, MTDATA, DPAB,DNTPD, DPA3B, PCzPCA1, PCzPCA2,PCzPCN1,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation:NPB or α-NPD),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD), and4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP);and carbazole derivatives, such as 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene(abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPA),9-phenyl-3-[4-(10-phenyl-9-anthryflphenyl]-9H-carbazole (abbreviation:PCzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

Other examples of the organic compound that can be used are aromatichydrocarbon compounds, such as2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),2-tert-butyl-9,10-di(1-naphthyl)anthracene,9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA),2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene(abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA),9,10-bis[2-(1-naphthyl)phenyl]-2-tert-butylanthracene,9,10-bis[2-(1-naphthyl)phenyl]anthracene, and2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene.

Other examples of the organic compound that can be used are aromatichydrocarbon compounds, such as2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9′-bianthryl,10,10′-diphenyl-9,9′-bianthryl,10,10′-bis(2-phenylphenyl)-9,9′-bianthryl,10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl, anthracene,tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene,pentacene, coronene, 4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation:DPVBi), and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene(abbreviation: DPVPA).

A high molecular compound such as PVK, PVTPA, PTPDMA, or Poly-TPD canalso be used.

Examples of the electron acceptor are organic compounds, such as7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ) and chloranil; oxides of transition metals; and oxides ofmetals that belong to Groups 4 to 8 in the periodic table. Specifically,vanadium oxide, niobium oxide, tantalum oxide, chromium oxide,molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide arepreferable because of their high electron accepting properties. Amongthese metal oxides, molybdenum oxide is especially preferable because itis stable in the air, has a low hygroscopic property, and is easilyhandled.

The hole-transport layer 702 is a layer containing a substance having ahigh hole-transport property. As the substance having a highhole-transport property, any of the following aromatic amine compoundscan be used, for example: NPB, TPD, BPAFLP,4,4′-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: DFLDPBi), and4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB). The substances mentioned here are mainly ones thathave a hole mobility of 10⁻⁶ cm²/V·s or higher. Note that other than theabove substances, any substance that has a property of transporting moreholes than electrons may be used.

For the hole-transport layer 702, a carbazole derivative such as CBP,CzPA, or PCzPA; an anthracene derivative such as t-BuDNA, DNA, orDPAnth; or a high molecular compound such as PVK, PVTPA, PTPDMA, orPoly-TPD can also be used.

For the light-emitting layer 703, a fluorescent compound which exhibitsfluorescence or a phosphorescent compound which exhibits phosphorescencecan be used.

Examples of the fluorescent compound that can be used for thelight-emitting layer 703 are the following light-emitting materials:materials that emit blue light, such asN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA), and4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA); materials that emit green light, such asN-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA),N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA),N-[9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA), and N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA); materials that emit yellow light, such asrubrene and 5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene(abbreviation: BPT); and materials that emit red light, such asN,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD) and7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD).

Examples of the phosphorescent compound that can be used for thelight-emitting layer 703 are the following light-emitting materials:materials that emit blue light, such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate(abbreviation: FIr6),bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)picolinate(abbreviation: FIrpic),bis{2-[3′,5′-bis(trifluoromethyl)phenyl]pyridinato-N,C^(2′)}iridium(III)picolinate(abbreviation: Ir(CF₃ppy)₂(pic)), andbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)acetylacetonate(abbreviation: FIr(acac)); materials that emit green light, such astris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃),bis(2-phenylpyridinato-N, C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(ppy)₂(acac)),bis(1,2-diphenyl-1H-benzimidazolato)iridium(III)acetylacetonate(abbreviation: Ir(pbi)₂(acac)), bis(benzoquinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)₂(acac)),and tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)₃);materials that emit yellow light, such asbis(2,4-diphenyl-1,3-oxazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(dpo)₂(acac)),bis[2-(4′-perfluorophenylphenyl)pyridinato]iridium(III)acetylacetonate(abbreviation: Ir(p-PF-ph)₂(acac)),bis(2-phenylbenzothiazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(bt)₂(acac)),(acetylacetonato)bis[2,3-bis(4-fluorophenyl)-5-methylpyrazinato]iridium(III)(abbreviation: Ir(Fdppr-Me)₂(acac)), and(acetylacetonato)bis[2-(4-methoxyphenyl)-3,5-dimethylpyrazinato]iridium(III)(abbreviation: Ir(dmmoppr)₂(acac)); materials that emit orange light,such as tris(2-phenylquinolinato-N,C^(2′))iridium(III) (abbreviation:Ir(pq)₃), bis(2-phenylquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(pq)₂(acac)),(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂(acac)), and(acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-iPr)₂(acac)); and materials that emit redlight, for example, organometallic complexes, such asbis[2-(2′-benzo[4,5-α]thienyl)pyridinato-N,C^(3′))iridium(III)acetylacetonate(abbreviation: Ir(btp)₂(acac)),bis(1-phenylisoquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(piq)₂(acac)),(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: Ir(Fdpq)₂(acac)),(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: Ir(tppr)₂(acac)),(dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: Ir(tppr)₂(dpm)), and(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin)platinum(II)(abbreviation: PtOEP). Further, rare-earth metal complexes, such astris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation:Tb(acac)₃(Phen)),tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III)(abbreviation: Eu(DBM)₃(Phen)), andtris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III)(abbreviation: Eu(TTA)₃(Phen)), exhibit light emission from rare-earthmetal ions (electron transition between different multiplicities), andthus can be used as phosphorescent compounds.

Note that the light-emitting layer 703 may have a structure in which anyof the above-described light-emitting organic compounds (alight-emitting substance or a guest material) is dispersed in anothersubstance (a host material). As the host material, a variety of kinds ofmaterials can be used, and it is preferable to use a substance which hasa lowest unoccupied molecular orbital level (LUMO level) higher thanthat of the guest material and has a highest occupied molecular orbitallevel (HOMO level) lower than that of the guest material.

Specific examples of the host material that can be used are thefollowing materials: metal complexes, such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq),bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), andbis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ);heterocyclic compounds, such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ),2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), andbathocuproine (abbreviation: BCP); condensed aromatic compounds, such as9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA),3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA),2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,9′-bianthryl (abbreviation: BANT),9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS),9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2),3,3′,3″-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3),9,10-diphenylanthracene (abbreviation: DPAnth), and6,12-dimethoxy-5,11-diphenylchrysene; aromatic amine compounds, such asN,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine(abbreviation: DPhPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA),N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine(abbreviation: PCAPBA),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), NPB (or α-NPD), TPD, DFLDPBi, and BSPB; and thelike.

A plurality of kinds of materials can be used as the host material. Forexample, in order to suppress crystallization, a substance such asrubrene which suppresses crystallization may be further added. Inaddition, NPB, Alq, or the like may be further added to efficientlytransfer energy to the guest material.

With a structure in which a guest material is dispersed in a hostmaterial, crystallization of the light-emitting layer 703 can besuppressed. Further, concentration quenching due to high concentrationof the guest material can be suppressed.

For the light-emitting layer 703, a high molecular compound can be used.Specific examples of a material that emits blue light arepoly(9,9-dioctylfluorene-2,7-diyl) (abbreviation: PFO),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,5-dimethoxybenzene-1,4-diyl)](abbreviation: PF-DMOP),poly{(9,9-dioctylfluorene-2,7-diyl)-co-[N,N′-di-(p-butylphenyl)-1,4-diaminobenzene]}(abbreviation: TAB-PFH), and the like. Specific examples of a materialthat emits green light are poly(p-phenylenevinylene) (abbreviation:PPV),poly[(9,9-dihexylfluorene-2,7-diyl)-alt-co-(benzo[2,1,3]thiadiazole-4,7-diyl)](abbreviation: PFBT),poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene)],and the like. Specific examples of a material that emits orange to redlight are poly[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylenevinylene](abbreviation: MEH-PPV), poly(3-butylthiophene-2,5-diyl) (abbreviation:R4-PAT), poly{[9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenylene]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]},poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-bis(1-cyanovinylenephenylene)]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]}(abbreviation: CN-PPV-DPD), and the like.

By providing a plurality of light-emitting layers and making theemission colors of the layers different from each other, light emissionof a desired color can be obtained from the light-emitting element as awhole. For example, by forming a light-emitting element having twolight-emitting layers such that the emission color of the firstlight-emitting layer and the emission color of the second light-emittinglayer are complementary colors, the light-emitting element can providewhite light emission as a whole. This can be applied to a light-emittingelement having three or more light-emitting layers.

The electron-transport layer 704 is a layer containing a substancehaving a high electron-transport property. As the substance having ahigh electron-transport property, for example, a metal complex having aquinoline skeleton or a benzoquinoline skeleton, such as Alq, Almq₃,BeBq₂, or Balq can be used. Alternatively, it is possible to use a metalcomplex having an oxazole-based ligand or a thiazole-based ligand, suchas bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂) orbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)₂).Further alternatively, instead of a metal complex, it is possible to usePBD, OXD-7, TAZ, Bphen, BCP, or the like. The substances mentioned hereare mainly ones that have an electron mobility of 10⁻⁶ cm²/V·s orhigher.

The electron-injection layer 705 is a layer containing a substancehaving a high electron-injection property. For the electron-injectionlayer 705, an alkali metal, an alkaline earth metal, or a compoundthereof, such as lithium, cesium, calcium, lithium fluoride, cesiumfluoride, calcium fluoride, or lithium oxide, can be used. A rare earthmetal compound such as erbium fluoride can also be used. Any of theabove substances for forming the electron-transport layer 704 can alsobe used.

Note that the hole-injection layer 701, the hole-transport layer 702,the light-emitting layer 703, the electron-transport layer 704, and theelectron-injection layer 705 which are described above can each beformed by a method such as an evaporation method (e.g., a vacuumevaporation method), an inkjet method, or a coating method.

The charge generation layer 709 illustrated in FIG. 6B can be formedusing the above-mentioned composite material. Further, the chargegeneration layer 709 may have a stacked-layer structure including alayer containing the composite material and a layer containing anothermaterial. In that case, as the layer containing another material, alayer containing an electron donating substance and a substance having ahigh electron-transport property, a layer formed using a transparentconductive film, or the like can be used.

The composite material layer 708 illustrated in FIG. 6C can be formedusing the above-described composite material in which an acceptorsubstance is mixed with an organic compound having a high hole-transportproperty.

For the electron-injection buffer layer 706, a substance having a highelectron-injection property, such as an alkali metal, an alkaline earthmetal, a rare earth metal, or a compound of the above metal (includingan oxide such as lithium oxide, a halide, and a carbonate such aslithium carbonate or cesium carbonate) can be used.

Further, in the case where the electron-injection buffer layer 706contains a substance having a high electron-transport property and adonor substance, the donor substance is preferably added so that themass ratio of the donor substance to the substance having a highelectron-transport property is in the range from 0.001:1 to 0.1:1. Notethat as the donor substance, an organic compound such astetrathianaphthacene (abbreviation: TTN), nickelocene, ordecamethylnickelocene can be used as well as an alkali metal, analkaline earth metal, a rare earth metal, and a compound of the abovemetal (including an oxide such as lithium oxide, a halide, and acarbonate such as lithium carbonate or cesium carbonate). Note that asthe substance having a high electron-transport property, a materialsimilar to the material for the electron-transport layer 704 describedabove can be used.

The electron-relay layer 707 contains a substance having a highelectron-transport property and is formed so that the LUMO level of thesubstance having a high electron-transport property is located betweenthe LUMO level of the acceptor substance contained in the compositematerial layer 708 and the LUMO level of the substance having a highelectron-transport property contained in the electron-transport layer704. In the case where the electron-relay layer 707 contains a donorsubstance, the donor level of the donor substance is controlled so as tobe located between the LUMO level of the acceptor substance contained inthe composite material layer 708 and the LUMO level of the substancehaving a high electron-transport property contained in theelectron-transport layer 704. As a specific value of the energy level,the LUMO level of the substance having a high electron-transportproperty contained in the electron-relay layer 707 is preferably higherthan or equal to −5.0 eV, more preferably higher than or equal to −5.0eV and lower than or equal to −3.0 eV.

As the substance having a high electron-transport property contained inthe electron-relay layer 707, a phthalocyanine-based material or a metalcomplex having a metal-oxygen bond and an aromatic ligand is preferablyused.

As the phthalocyanine-based material contained in the electron-relaylayer 707, specifically, any of CuPc, a phthalocyanine tin(II) complex(SnPc), a phthalocyanine zinc complex (ZnPc), cobalt(II) phthalocyanine,β-form (CoPc), phthalocyanine iron (FePc), and vanadyl2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine (PhO-VOPc), is preferablyused.

As the metal complex having a metal-oxygen bond and an aromatic ligand,which is contained in the electron-relay layer 707, a metal complexhaving a metal-oxygen double bond is preferably used. The metal-oxygendouble bond has an acceptor property (a property of easily acceptingelectrons); thus, electrons can be transferred (donated and accepted)more easily.

As a metal complex having a metal-oxygen bond and an aromatic ligand, aphthalocyanine-based material is preferable. Specifically, vanadylphthalocyanine (VOPc), a phthalocyanine tin(IV) oxide complex (SnOPc),or a phthalocyanine titanium oxide complex (TiOPc) is preferable becausea metal-oxygen double bond is more likely to act on another molecule interms of a molecular structure and an acceptor property is high.

Note that as the phthalocyanine-based material described above, aphthalocyanine-based material having a phenoxy group is preferable.Specifically, a phthalocyanine derivative having a phenoxy group, suchas PhO-VOPc, is preferable. The phthalocyanine derivative having aphenoxy group is soluble in a solvent and therefore has the advantage ofbeing easy to handle during formation of a light-emitting element andthe advantage of facilitating maintenance of an apparatus used for filmformation.

The electron-relay layer 707 may further contain a donor substance. Asthe donor substance, an organic compound such as TTN, nickelocene, ordecamethylnickelocene can be used as well as an alkali metal, analkaline earth metal, a rare earth metal, and a compound of the abovemetal (including an oxide such as lithium oxide, a halide, and acarbonate such as lithium carbonate or cesium carbonate). When such adonor substance is contained in the electron-relay layer 707, electronscan be transferred easily and the light-emitting element can be drivenat lower voltage.

In the case where a donor substance is contained in the electron-relaylayer 707, in addition to the materials described above, a substancehaving a LUMO level higher than the acceptor level of the acceptorsubstance contained in the composite material layer 708 can be used asthe substance having a high electron-transport property. Specifically,it is preferable to use a substance having a LUMO level higher than orequal to −5.0 eV, preferably higher than or equal to −5.0 eV and lowerthan or equal to −3.0 eV. Examples of such a substance are a perylenederivative and a nitrogen-containing condensed aromatic compound. Notethat a nitrogen-containing condensed aromatic compound is preferablyused for the electron-relay layer 707 because of its stability.

Specific examples of the perylene derivative are3,4,9,10-perylenetetracarboxylic dianhydride (abbreviation: PTCDA),3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (abbreviation:PTCBI), N,N′-dioctyl-3,4,9,10-perylenetetracarboxylic diimide(abbreviation: PTCDI-C8H), N,N′-dihexyl-3,4,9,10-perylenetetracarboxylicdiimide (abbreviation: Hex PTC), and the like.

Specific examples of the nitrogen-containing condensed aromatic compoundare pirazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(abbreviation: PPDN),2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation:HAT(CN)₆), 2,3-diphenylpyrido[2,3-b]pyrazine (abbreviation: 2PYPR),2,3-bis(4-fluorophenyl)pyrido[2,3-b]pyrazine (abbreviation: F2PYPR), andthe like.

Besides, 7,7,8,8-tetracyanoquinodimethane (abbreviation: TCNQ),1,4,5,8-naphthalenetetracarboxylic dianhydride (abbreviation: NTCDA),perfluoropentacene, copper hexadecafluorophthalocyanine (abbreviation:F₁₆CuPc),N,N-bis(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl)-1,4,5,8-naphthalenetetracarboxylicdiimide (abbreviation: NTCDI-C8F),3′,4′-dibutyl-5,5″-bis(dicyanomethylene)-5,5″-dihydro-2,2′:5′,2″-terthiophene(abbreviation: DCMT), methanofullerenes (e.g., [6,6]-phenyl C₆₁ butyricacid methyl ester), or the like can be used.

Note that in the case where a donor substance is contained in theelectron-relay layer 707, the electron-relay layer 707 may be formed bya method such as co-evaporation of the substance having a highelectron-transport property and the donor substance.

In the above manner, the EL layer in this embodiment can be formed.

This embodiment can be freely combined with any of the otherembodiments.

Embodiment 5

In this embodiment, with reference to FIGS. 7A to 7E, FIG. 8, and FIGS.9A to 9C, description is given of examples of a variety of electronicdevices and lighting devices that are each completed by use of alight-emitting device of one embodiment of the present invention.

In the light-emitting device of one embodiment of the present invention,deterioration of an organic EL element due to impurities such asmoisture or oxygen is suppressed. Thus, highly reliable electronicdevice and lighting device can be obtained by application of thelight-emitting device of one embodiment of the present invention.

Examples of the electronic devices to which the light-emitting device isapplied are a television device (also referred to as television ortelevision receiver), a monitor of a computer or the like, a camera suchas a digital camera or a digital video camera, a digital photo frame, amobile phone (also referred to as cellular phone or cellular phonedevice), a portable game machine, a portable information terminal, anaudio reproducing device, and a large-sized game machine such as apachinko machine. Specific examples of these electronic devices and alighting device are illustrated in FIGS. 7A to 7E, FIG. 8, and FIGS. 9Ato 9C.

FIG. 7A illustrates an example of a television device. In a televisiondevice 7100, a display portion 7103 is incorporated in a housing 7101.The display portion 7103 is capable of displaying images, and thelight-emitting device of one embodiment of the present invention can beused for the display portion 7103. A highly reliable television devicecan be obtained by using the light-emitting device of one embodiment ofthe present invention for the display portion 7103. Here, the housing7101 is supported by a stand 7105.

Operation of the television device 7100 can be performed with anoperation switch of the housing 7101 or a separate remote controller7110. With operation keys 7109 of the remote controller 7110, channelsand volume can be controlled and images displayed on the display portion7103 can be controlled. Furthermore, the remote controller 7110 may beprovided with a display portion 7107 for displaying data output from theremote controller 7110.

Note that the television device 7100 is provided with a receiver, amodern, and the like. With the receiver, a general television broadcastcan be received. Furthermore, when the television device 7100 isconnected to a communication network by wired or wireless connection viathe modem, one-way (from a transmitter to a receiver) or two-way(between a transmitter and a receiver, between receivers, or the like)data communication can be performed.

FIG. 7B illustrates a computer having a main body 7201, a housing 7202,a display portion 7203, a keyboard 7204, an external connection port7205, a pointing device 7206, and the like. Note that this computer ismanufactured using the light-emitting device of one embodiment of thepresent invention for the display portion 7203. A highly reliablecomputer can be obtained by using the light-emitting device of oneembodiment of the present invention for the display portion 7203.

FIG. 7C illustrates a portable game machine having two housings, ahousing 7301 and a housing 7302, which are connected with a jointportion 7303 so that the portable game machine can be opened or folded.A display portion 7304 is incorporated in the housing 7301, and adisplay portion 7305 is incorporated in the housing 7302. In addition,the portable game machine illustrated in FIG. 7C includes a speakerportion 7306, a recording medium insertion portion 7307, an LED lamp7308, input means (an operation key 7309, a connection terminal 7310, asensor 7311 (a sensor having a function of measuring force,displacement, position, speed, acceleration, angular velocity,rotational frequency, distance, light, liquid, magnetism, temperature,chemical substance, sound, time, hardness, electric field, current,voltage, electric power, radiation, flow rate, humidity, gradient,oscillation, odor, or infrared rays), and a microphone 7312), and thelike. Needless to say, the structure of the portable game machine is notlimited to the above as long as the light-emitting device of oneembodiment of the present invention is used for at least one of thedisplay portion 7304 and the display portion 7305, and may include otheraccessories as appropriate. A highly reliable portable game machine canbe obtained by using the light-emitting device of one embodiment of thepresent invention for the display portion 7304 and/or the displayportion 7305. The portable game machine illustrated in FIG. 7C has afunction of reading out a program or data stored in a storage medium todisplay it on the display portion, and a function of sharing informationwith another portable game machine by wireless communication. Theportable game machine illustrated in FIG. 7C can have a variety offunctions without limitation to the above.

FIG. 7D illustrates an example of a mobile phone. A mobile phone 7400 isprovided with a display portion 7402 incorporated in a housing 7401,operation buttons 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. Note that the mobile phone 7400is manufactured using the light-emitting device of one embodiment of thepresent invention for the display portion 7402. A highly reliable mobilephone can be obtained by using the light-emitting device of oneembodiment of the present invention for the display portion 7402.

When the display portion 7402 of the mobile phone 7400 illustrated inFIG. 7D is touched with a finger or the like, data can be input into themobile phone 7400. Further, operations such as making a call andcomposing an e-mail can be performed by touching the display portion7402 with a finger or the like.

There are mainly three screen modes of the display portion 7402. Thefirst mode is a display mode mainly for displaying images. The secondmode is an input mode mainly for inputting data such as text. The thirdmode is a display-and-input mode in which two modes of the display modeand the input mode are combined.

For example, in the case of making a call or composing an e-mail, a textinput mode mainly for inputting text is selected for the display portion7402 so that text displayed on the screen can be inputted. In this case,it is preferable to display a keyboard or number buttons on almost theentire screen of the display portion 7402.

When a detection device including a sensor for detecting inclination,such as a gyroscope or an acceleration sensor, is provided inside themobile phone 7400, display on the screen of the display portion 7402 canbe automatically switched by determining the orientation of the mobilephone 7400 (whether the mobile phone is placed horizontally orvertically for a landscape mode or a portrait mode).

The screen modes are switched by touching the display portion 7402 oroperating the operation buttons 7403 of the housing 7401. The screenmodes can also be switched depending on the kind of image displayed onthe display portion 7402. For example, when a signal of an imagedisplayed on the display portion is a signal of moving image data, thescreen mode is switched to the display mode. When the signal is a signalof text data, the screen mode is switched to the input mode.

Moreover, in the input mode, when input by touching the display portion7402 is not performed for a certain period while a signal detected by anoptical sensor in the display portion 7402 is detected, the screen modemay be controlled so as to be switched from the input mode to thedisplay mode.

The display portion 7402 may function as an image sensor. For example,an image of a palm print, a fingerprint, or the like is taken when thedisplay portion 7402 is touched with the palm or the finger, wherebypersonal authentication can be performed. Further, by providing abacklight or a sensing light source which emits near-infrared light inthe display portion, an image of a finger vein, a palm vein, or the likecan be taken.

FIG. 7E illustrates a desk lamp, which includes a lighting portion 7501,a shade 7502, an adjustable arm 7503, a support 7504, a base 7505, and apower switch 7506. The desk lamp is manufactured using thelight-emitting device of one embodiment of the present invention for thelighting portion 7501. A highly reliable desk lamp can be obtained byusing the light-emitting device of one embodiment of the presentinvention for the display portion 7501. Note that the “lighting device”also includes ceiling lights, wall lights, and the like.

FIG. 8 illustrates an example in which the light-emitting device of oneembodiment of the present invention is used for an interior lightingdevice 8111. Since the light-emitting device of one embodiment of thepresent invention can have a larger area, it can be used as a large-arealighting device. Furthermore, the light-emitting device can be used as aroll-type lighting device 8112. As illustrated in FIG. 8, a desk lamp8113 described with reference to FIG. 7E may also be used in a roomprovided with the interior lighting device 8111.

FIGS. 9A and 9B illustrate a foldable tablet terminal. The tabletterminal is opened in FIG. 9A. The tablet terminal includes a housing9630, a display portion 9631 a, a display portion 9631 b, a display modeswitch 9034, a power switch 9035, a power saver switch 9036, a clasp9033, and an operation switch 9038.

The light-emitting device of one embodiment of the present invention canbe applied to the display portion 9631 a or the display portion 9631 b.

Part of the display portion 9631 a can be a touch panel region 9632 aand data can be input when a displayed operation key 9037 is touched.Although a structure in which a half region in the display portion 9631a has only a display function and the other half region also has a touchpanel function is shown as an example, the display portion 9631 a is notlimited to the structure. The whole region in the display portion 9631 amay have a touch panel function. For example, the display portion 9631 acan display keyboard buttons in the whole region to be a touch panel,and the display portion 9631 b can be used as a display screen.

Similarly to the display portion 9631 a, part of the display portion9631 b can be a touch panel region 9632 b. A switching button 9639 forshowing/hiding a keyboard of the touch panel is touched with a finger, astylus, or the like, so that keyboard buttons can be displayed on thedisplay portion 9631 b.

Touch input can be performed in the touch panel region 9632 a and thetouch panel region 9632 b at the same time.

The display mode switch 9034 can switch the display between portraitmode, landscape mode, and the like, and between monochrome display andcolor display, for example. The power saver switch 9036 can controldisplay luminance in accordance with the amount of external light in useof the tablet terminal detected by an optical sensor incorporated in thetablet terminal. Another detection device including a sensor fordetecting inclination, such as a gyroscope or an acceleration sensor,may be incorporated in the tablet terminal, in addition to the opticalsensor.

Note that FIG. 9A shows an example in which the display portion 9631 aand the display portion 9631 b have the same display area; however,without limitation thereon, one of the display portions may be differentfrom the other display portion in size and display quality. For example,one display panel may be capable of higher-definition display than theother display panel.

The tablet terminal is closed in FIG. 9B. The tablet terminal includesthe housing 9630, a solar cell 9633, a charge and discharge controlcircuit 9634, a battery 9635, and a DCDC converter 9636. In FIG. 9B, astructure including the battery 9635 and the DCDC converter 9636 isillustrated as an example of the charge and discharge control circuit9634.

Since the tablet terminal is foldable, the housing 9630 can be closedwhen the tablet terminal is not used. As a result, the display portion9631 a and the display portion 9631 b can be protected; thus, a tabletterminal which has excellent durability and excellent reliability interms of long-term use can be provided.

In addition, the tablet terminal illustrated in FIGS. 9A and 9B can havea function of displaying a variety of kinds of data (e.g., a stillimage, a moving image, and a text image), a function of displaying acalendar, a date, the time, or the like on the display portion, atouch-input function of operating or editing the data displayed on thedisplay portion by touch input, a function of controlling processing bya variety of kinds of software (programs), and the like.

The solar cell 9633 provided on a surface of the tablet terminal cansupply power to the touch panel, the display portion, a video signalprocessing portion, or the like. Note that a structure in which thesolar cell 9633 is provided on one or two surfaces of the housing 9630is preferable to charge the battery 9635 efficiently. When a lithium ionbattery is used as the battery 9635, there is an advantage of downsizingor the like.

The structure and the operation of the charge and discharge controlcircuit 9634 illustrated in FIG. 9B will be described with reference toa block diagram in FIG. 9C. The solar cell 9633, the battery 9635, theDCDC converter 9636, a converter 9637, switches SW1 to SW3, and thedisplay portion 9631 are illustrated in FIG. 9C, and the battery 9635,the DCDC converter 9636, the converter 9637, and the switches SW1 to SW3correspond to the charge and discharge control circuit 9634 illustratedin FIG. 9B.

First, an example of the operation in the case where power is generatedby the solar cell 9633 using external light is described. The voltage ofpower generated by the solar battery is raised or lowered by the DCDCconverter 9636 so that the power has a voltage for charging the battery9635. Then, when the power from the solar cell 9633 is used for theoperation of the display portion 9631, the switch SW1 is turned on andthe voltage of the power is raised or lowered by the converter 9637 soas to be a voltage needed for the display portion 9631. In addition,when display on the display portion 9631 is not performed, the switchSW1 is turned off and the switch SW2 is turned on so that charge of thebattery 9635 may be performed.

Note that the solar cell 9633 is described as an example of a powergeneration means; however, without limitation thereon, the battery 9635may be charged using another power generation means such as apiezoelectric element or a thermoelectric conversion element (Peltierelement). For example, a non-contact electric power transmission modulewhich transmits and receives power wirelessly (contactlessly) to chargethe battery 9635, or a combination of the solar cell 9633 and anothermeans for charge may be used.

As described above, electronic devices and lighting devices can beobtained by application of the light-emitting device of one embodimentof the present invention. The light-emitting device of one embodiment ofthe present invention has a remarkably wide application range, and canbe applied to electronic devices in a variety of fields.

Note that the structure described in this embodiment can be combinedwith the structure described in any of the above embodiments asappropriate.

Example 1

In this example, a light-emitting device of one embodiment of thepresent invention will be described with reference to FIGS. 11A to 11D,FIGS. 12A to 12C, and FIGS. 13A1, 13A2, 13B1, 13B2, 13C1, 13C2, 13D1,and 13D2.

In this example, a light-emitting device of one embodiment of thepresent invention and a light-emitting device of a comparative examplewere fabricated. In the light-emitting device of one embodiment of thepresent invention, a glass layer 1053 a and a resin layer 1053 bcontaining a dry agent were used as sealants. In the light-emittingdevice of the comparative example, only the glass layer 1053 a was usedas a sealant.

First, a method for manufacturing the light-emitting device of oneembodiment of the present invention will be described.

{First Step: Formation of Light-Emitting Portion}

First, light-emitting portions 1002 were formed over a first substrate1001 (FIG. 11A). In this example, four light-emitting portions 1002 werefilmed over the first substrate 1001. FIG. 11C is a cross-sectional viewof one of the light-emitting portions 1002.

Specifics are as follows: a 300-nm-thick silicon oxynitride film wasformed as a base film 1011; a 100-nm-thick titanium film, a 600-nm-thickaluminum film, and a 200-nm-thick titanium film were stacked as anextraction electrode 1013; a 200-nm-thick silicon oxide film was formedas an insulating film 1015; a 200-nm-thick aluminum-nickel alloy filmcontaining lanthanum and a 6-nm-thick titanium film were stacked as afirst electrode 1017 of an organic EL element; a 1.5-μm-thick polyimidefilm was formed as a partition 1019 covering an end portion of the firstelectrode 1017; an EL layer 1021 was formed over the first electrode1017; and a 15-nm-thick magnesium-silver alloy film and a 70-nm-thickindium tin oxide film were stacked as a second electrode 1023 over theEL layer 1021.

{Second Step: Formation of Sealant}

The glass layer 1053 a and the resin layer 1053 b containing the dryagent were formed over a second substrate 1003 (FIG. 11B).

Specifically, a frit paste was formed over the second substrate 1003 bya screen printing method. As the fit paste, a glass paste containingbismuth oxide or the like was used.

Then, drying was performed at 140° C. for 20 minutes.

Next, an organic solvent and a resin in the frit paste were removed bylaser light irradiation to form the glass layer 1053 a, which is a firstsealant. The laser light irradiation was performed under the followingconditions: a semiconductor laser with a wavelength of 940 nm was used,the output power was 15 W, and the scanning speed was 1 mm/sec.

After the second substrate 1003 was washed, heat treatment was performedat 200° C. under atmospheric pressure for 60 minutes. Then, the secondsubstrate 1003 was put in a bonding apparatus and heat treatment wasperformed at 170° C. under reduced pressure for 30 minutes.

Next, the resin layer 1053 b containing the dry agent, which is a secondsealant, was formed so as to surround the glass layer 1053 a. Here, aphotocurable resin containing zeolite was used. At that time, a resinlayer 1055 for temporal fixing was also formed along the periphery of asurface of the second substrate 1003 over which the glass layer 1053 awas formed.

{Third Step: Sealing with Resin Layer}

The first substrate 1001 and the second substrate 1003 were bonded toeach other while force of 0.6 kN was applied under reduced pressure(pressure of 100 Pa) so that the substrates were closely in contact withthe resin layer 1053 b.

Then, the resin layer 1053 b and the resin layer 1055 were irradiatedwith ultraviolet light so that the resin layer 1053 b and the resinlayer 1055 were cured. After that, heat treatment was performed at 80°C. for 60 minutes. The ultraviolet light irradiation was performed fromthe second substrate 1003 side.

{Fourth Step: Sealing with Glass Layer}

The light-emitting device sealed with the resin layer was taken out fromthe bonding apparatus and then, the glass layer 1053 a was irradiatedwith laser light under atmospheric pressure. Accordingly, glass wasmelted to be bonded to the first substrate 1001 and the second substrate1003 at their respective connection portions. The laser lightirradiation was performed under the following conditions: asemiconductor laser with a wavelength of 940 nm was used, the outputpower was 8 W, and the scanning speed was 1 mm/sec. The laser lightirradiation was performed from the second substrate 1003 side.

FIG. 11D is a cross-sectional view illustrating that one light-emittingportion 1002 is sealed with the first substrate 1001, the secondsubstrate 1003, the glass layer 1053 a, and the resin layer 1053 bcontaining the dry agent.

The first substrate 1001 was divided along dotted lines in FIG. 12A,whereby four light-emitting devices of one embodiment of the presentinvention were obtained.

Next, a method for manufacturing the light-emitting device of thecomparative example will be described.

A first step, formation of the glass layer 1053 a in a second step, anda fourth step were performed to manufacture the light-emitting device ofthe comparative example, in a manner similar to that of thelight-emitting device of one embodiment of the present invention. In thesecond step, only the resin layer 1055 for temporal fixing was formed.In a third step, the resin layer 1055 was cured. A formation method, acuring method, and the like, of the resin layer 1055 were similar tothose of the light-emitting device of one embodiment of the presentinvention.

FIG. 12B is a plan view of the fabricated light-emitting device of thecomparative example (before divided into four), and FIG. 12C is across-sectional view illustrating that one light-emitting portion 1002is sealed with the first substrate 1001, the second substrate 1003, andthe glass layer 1053 a.

Then, the light-emitting device of one embodiment of the presentinvention and the light-emitting device of the comparative example weresubjected to a preservation test. Specifically, the light-emittingdevices were preserved in a thermostatic bath maintained at atemperature of 65° C. and a humidity of 90%, and light emission wasobserved at room temperature (in an atmosphere maintained at 25° C.)after a certain period of time.

FIGS. 13A1, 13B1, and 13C1 are photographs showing light emission of thelight-emitting device of one embodiment of the present invention beforethe preservation test, after preservation for 500 hours, and afterpreservation for 1000 hours, respectively.

FIGS. 13A2, 13B2, and 13C2 are photographs showing light emission of thelight-emitting device of the comparative example before the preservationtest, after preservation for 500 hours, and after preservation for 1000hours, respectively.

FIG. 13D1 is a photograph of a sealing portion (the glass layer 1053 aand the resin layer 1053 b) of the light-emitting device of oneembodiment of the present invention, and FIG. 13D2 is a photograph of asealing portion (the glass layer 1053 a) of the light-emitting device ofthe comparative example.

As shown in FIGS. 13A1, 13B1, and 13C1, in the light-emitting device ofone embodiment of the present invention, light emission that wasequivalent to that before the preservation test was observed even afterpreservation for 1000 hours.

In contrast, as shown in FIGS. 13A2, 13B2, and 13C2, in thelight-emitting device of the comparative example, the entirelight-emitting portion emitted light with substantially the sameluminance before the preservation test; however, light emission in anend portion of the light-emitting portion was darker than that in thecentral portion after preservation for 500 hours. Accordingly, it isfound that shrinkage of the light-emitting portion (here, luminancedegradation from the end portion of the light-emitting portion, or anincrease in non-light-emitting region in the light-emitting portion)occurs. In addition, the shrinkage of the light-emitting portionprogressed after preservation for 1000 hours.

As a cause of the shrinkage of the light-emitting portion, entry ofimpurities such as moisture or oxygen into the light-emitting portion(specifically, into the organic EL element) can be given. For example,impurities remaining in the substrate may be released by the heattreatment in the second step or the like and may enter thelight-emitting portion. Since the light-emitting device is in the airafter sealing with the resin layer is performed, atmospheric componentsmay enter the light-emitting device, or even the light-emitting portionbefore sealing with the glass layer is performed. For another example,impurities contained in the glass layer may be released at the time ofthe laser light irradiation or the like and enter the light-emittingportion. Atmospheric components may enter the light-emitting device notonly during the manufacturing process but also after the manufacturingprocess, depending on the degree of sealing of the light-emittingdevice.

The light-emitting device of one embodiment of the present inventionincludes the resin layer containing the dry agent as the sealant,whereby the effect of sealing the organic EL element can be increased ascompared to the case where only the glass layer is used as the sealant.For example, when impurities remaining in the light-emitting device orimpurities having entered the light-emitting device are adsorbed, entryof the impurities into the organic EL element can be suppressed.Further, the adhesion between the substrates of the light-emittingdevice can be increased and thus entry of atmospheric components intothe light-emitting device can be suppressed.

The above results indicate that deterioration of the organic EL elementcan be suppressed in the light-emitting device of one embodiment of thepresent invention, which is sealed with the glass layer and the resinlayer containing the dry agent, as compared to the light-emitting deviceof the comparative example, which is sealed with only the glass layer.

EXPLANATION OF REFERENCE

-   -   114: first insulating layer, 116: second insulating layer, 118:        first electrode, 120: EL layer, 120 a: first EL layer, 120 b:        second EL layer, 122: second electrode, 124: insulating layer,        130: light-emitting element, 140 a: transistor, 140 b:        transistor, 152: transistor, 153: transistor, 164: black matrix,        166: color filter, 168: overcoat, 701: hole-injection layer,        702: hole-transport layer, 703: light-emitting layer, 704:        electron-transport layer, 705: electron-injection layer, 706:        electron-injection buffer layer, 707: electron-relay layer, 708:        composite material layer, 709: charge generation layer, 801:        first substrate, 802: light-emitting portion, 803: driver        circuit portion, 804: driver circuit portion, 805 a: first        sealant, 805 b: second sealant, 805 c: first sealant, 805 d:        second sealant, 806: second substrate, 811: second space, 813:        first space, 815: dry agent, 1001: first substrate, 1002:        light-emitting portion, 1003: second substrate, 1011: base film,        1013: extraction electrode, 1015: insulating film, 1017: first        electrode, 1019: partition, 1021: EL layer, 1023: second        electrode, 1053 a: glass layer, 1053 b: resin layer, 1055: resin        layer, 7100: television device, 7101: housing, 7103: display        portion, 7105: stand, 7107: display portion, 7109: operation        key, 7110: remote controller, 7201: main body, 7202: housing,        7203: display portion, 7204: keyboard, 7205: external connection        port, 7206: pointing device, 7301: housing, 7302: housing, 7303:        connection portion, 7304: display portion, 7305: display        portion, 7306: speaker portion, 7307: recording medium insertion        portion, 7308: LED lamp, 7309: operation key, 7310: connection        terminal, 7311: sensor, 7312: microphone, 7400: mobile phone,        7401: housing, 7402: display portion, 7403: operation button,        7404: external connection port, 7405: speaker, 7406: microphone,        7501: lighting portion, 7502: shade, 7503: adjustable arm, 7504:        support, 7505: base, 7506: power switch, 8111: lighting device,        8112: lighting device, 8113: desk lamp, 9033: clasp, 9034:        switch, 9035: power switch, 9036: switch, 9037: operation key,        9038: operation switch, 9630: housing, 9631: display portion,        9631 a: display portion, 9631 b: display portion, 9632 a:        region, 9632 b: region, 9633: solar cell, 9634: charge and        discharge control circuit, 9635: battery, 9636: DCDC converter,        9637: converter, and 9639: button.

This application is based on Japanese Patent Application serial no.2011-184779 filed with Japan Patent Office on Aug. 26, 2011, the entirecontents of which are hereby incorporated by reference.

What is claimed is: 1-14. (canceled)
 15. A method for manufacturing alight-emitting device, comprising the steps of: providing a firstelectrode over a first substrate, a layer containing a light-emittingorganic compound over the first electrode, and a second electrode overthe layer to form a light-emitting element, whereby a light-emittingportion is formed; applying a frit paste over a second substrate andheating to form a glass layer; applying a resin including a dry agentover the second substrate in an inert atmosphere to form a resin layer;providing the first substrate and the second substrate so as to faceeach other; irradiating the resin layer with light under reducedpressure to form a closed space surrounded by the resin layer, the firstsubstrate, and the second substrate; and irradiating the glass layerwith laser light in the air to form a closed space surrounded by theglass layer, the first substrate, and the second substrate, wherein theglass layer is provided so as to surround the light-emitting portion andthe resin layer is provided so as to surround the glass layer.
 16. Themethod for manufacturing a light-emitting device, according to claim 15,wherein the resin layer comprises a photocurable resin.
 17. The methodfor manufacturing a light-emitting device, according to claim 15,wherein the step of irradiating the glass layer with laser light isperformed from the second substrate side.
 18. The method formanufacturing a light-emitting device, according to claim 15, furthercomprising a step of heat treatment before the step of irradiating theglass layer with laser light.
 19. The method for manufacturing alight-emitting device, according to claim 15, wherein the frit pastecomprises an absorber which absorbs light having a wavelength of thelaser light.
 20. The method for manufacturing a light-emitting device,according to claim 15, further comprising a step of planarizing a topsurface of the glass layer.
 21. The method for manufacturing alight-emitting device, according to claim 15, wherein the step ofirradiating the resin layer with light is performed with use of ashielding plate.
 22. A method for manufacturing a light-emitting device,comprising the steps of: providing a first electrode over a firstsubstrate, a layer containing a light-emitting organic compound over thefirst electrode, and a second electrode over the layer to form alight-emitting element, whereby a light-emitting portion is formed;applying a fit paste over a second substrate and heating to form a glasslayer; applying a resin including a first dry agent over the secondsubstrate in an inert atmosphere to form a resin layer; providing asecond dry agent over the second substrate; providing the firstsubstrate and the second substrate so as to face each other; irradiatingthe resin layer with light under reduced pressure to form a closed spacesurrounded by the resin layer, the first substrate, and the secondsubstrate; and irradiating the glass layer with laser light in the airto form a closed space surrounded by the glass layer, the firstsubstrate, and the second substrate, wherein the glass layer is providedso as to surround the light-emitting portion and the resin layer isprovided so as to surround the glass layer.
 23. The method formanufacturing a light-emitting device, according to claim 22, whereinthe resin layer comprises a photocurable resin.
 24. The method formanufacturing a light-emitting device, according to claim 22, whereinthe step of irradiating the glass layer with laser light is performedfrom the second substrate side.
 25. The method for manufacturing alight-emitting device, according to claim 22, further comprising a stepof heat treatment before the step of irradiating the glass layer withlaser light.
 26. The method for manufacturing a light-emitting device,according to claim 22, wherein the fit paste comprises an absorber whichabsorbs light having a wavelength of the laser light.
 27. The method formanufacturing a light-emitting device, according to claim 22, furthercomprising a step of planarizing a top surface of the glass layer. 28.The method for manufacturing a light-emitting device, according to claim22, wherein the step of irradiating the resin layer with light isperformed with use of a shielding plate.